GENEVA, Switzerland (AFP) — The International Organisation for Migration warned on Friday the world must prepare for a mass increase in climate-linked migration as leaders battled to save a deal on global warming in Copenhagen.

“Climate change and environmental degradation are already triggering migration or displacement all over the planet,” the IOM warned on the critical last day of the Denmark summit, which coincides with International Migrants Day.

Right now, “it is the world’s poorest countries that are bearing the brunt” of the migration, said the Geneva-based body, calling for leaders to make “greater efforts, beyond Copenhagen,” to tackle the complex issue.

IOM director general William Lacy Swing said experts still struggle to measure the number of people worldwide who choose to leave or are driven from their homes because of climate change and environmental degradation.

But he said the IOM has established beyond doubt that environmental migration “is a growing trend” and that “climate change, demographic trends and globalisation all point to more migration in the future”.

The IOM pointed at several Asian countries already struggling to cope with mass migration from rural areas to cities, as farmers’ livelihoods are destroyed by recurrent floods.

In many cases, it argued, migration is a valuable “coping mechanism” for populations struggling with environmental degradation, such as in Mali where thousands have left drought-stricken areas in recent years.

But developing nations will need help to cope with large-scale environmental migration, it said, urging the rich world to unblock financial aid, over and above existing development assistance.

And climate-linked emigration from hotspots in Asia, Africa, Central and Latin America will also pose a major challenge to the developed world, the IOM said, warning policymakers have yet to grasp the scale of the issue.

Swing said the world had a duty to “manage migration in a way that increases the benefits and opportunities and reduces suffering”.

“The effects of climate change will be an increasingly important variable in this equation. We need to think ahead and plan for change. We need to be prepared to respond to the humanitarian challenges that climate change is already posing today.”